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92703eee PM |
1 | /* |
2 | * NetBIOS name service broadcast connection tracking helper | |
3 | * | |
4 | * (c) 2005 Patrick McHardy <kaber@trash.net> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | /* | |
12 | * This helper tracks locally originating NetBIOS name service | |
13 | * requests by issuing permanent expectations (valid until | |
14 | * timing out) matching all reply connections from the | |
15 | * destination network. The only NetBIOS specific thing is | |
16 | * actually the port number. | |
17 | */ | |
18 | #include <linux/kernel.h> | |
19 | #include <linux/module.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/skbuff.h> | |
22 | #include <linux/netdevice.h> | |
23 | #include <linux/inetdevice.h> | |
24 | #include <linux/if_addr.h> | |
25 | #include <linux/in.h> | |
26 | #include <linux/ip.h> | |
1863f096 | 27 | #include <linux/netfilter.h> |
92703eee PM |
28 | #include <net/route.h> |
29 | ||
30 | #include <net/netfilter/nf_conntrack.h> | |
31 | #include <net/netfilter/nf_conntrack_helper.h> | |
32 | #include <net/netfilter/nf_conntrack_expect.h> | |
33 | ||
34 | #define NMBD_PORT 137 | |
35 | ||
36 | MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); | |
37 | MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper"); | |
38 | MODULE_LICENSE("GPL"); | |
39 | MODULE_ALIAS("ip_conntrack_netbios_ns"); | |
40 | ||
41 | static unsigned int timeout __read_mostly = 3; | |
42 | module_param(timeout, uint, 0400); | |
43 | MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds"); | |
44 | ||
3db05fea | 45 | static int help(struct sk_buff *skb, unsigned int protoff, |
601e68e1 | 46 | struct nf_conn *ct, enum ip_conntrack_info ctinfo) |
92703eee PM |
47 | { |
48 | struct nf_conntrack_expect *exp; | |
3db05fea | 49 | struct iphdr *iph = ip_hdr(skb); |
ee6b9673 | 50 | struct rtable *rt = skb->rtable; |
92703eee PM |
51 | struct in_device *in_dev; |
52 | __be32 mask = 0; | |
53 | ||
54 | /* we're only interested in locally generated packets */ | |
3db05fea | 55 | if (skb->sk == NULL) |
92703eee PM |
56 | goto out; |
57 | if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST)) | |
58 | goto out; | |
59 | if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) | |
60 | goto out; | |
61 | ||
62 | rcu_read_lock(); | |
63 | in_dev = __in_dev_get_rcu(rt->u.dst.dev); | |
64 | if (in_dev != NULL) { | |
65 | for_primary_ifa(in_dev) { | |
66 | if (ifa->ifa_broadcast == iph->daddr) { | |
67 | mask = ifa->ifa_mask; | |
68 | break; | |
69 | } | |
70 | } endfor_ifa(in_dev); | |
71 | } | |
72 | rcu_read_unlock(); | |
73 | ||
74 | if (mask == 0) | |
75 | goto out; | |
76 | ||
6823645d | 77 | exp = nf_ct_expect_alloc(ct); |
92703eee PM |
78 | if (exp == NULL) |
79 | goto out; | |
80 | ||
81 | exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple; | |
82 | exp->tuple.src.u.udp.port = htons(NMBD_PORT); | |
83 | ||
84 | exp->mask.src.u3.ip = mask; | |
85 | exp->mask.src.u.udp.port = htons(0xFFFF); | |
92703eee PM |
86 | |
87 | exp->expectfn = NULL; | |
88 | exp->flags = NF_CT_EXPECT_PERMANENT; | |
6002f266 | 89 | exp->class = NF_CT_EXPECT_CLASS_DEFAULT; |
88044c8c | 90 | exp->helper = NULL; |
92703eee | 91 | |
6823645d PM |
92 | nf_ct_expect_related(exp); |
93 | nf_ct_expect_put(exp); | |
92703eee | 94 | |
3db05fea | 95 | nf_ct_refresh(ct, skb, timeout * HZ); |
92703eee PM |
96 | out: |
97 | return NF_ACCEPT; | |
98 | } | |
99 | ||
6002f266 PM |
100 | static struct nf_conntrack_expect_policy exp_policy = { |
101 | .max_expected = 1, | |
102 | }; | |
103 | ||
92703eee PM |
104 | static struct nf_conntrack_helper helper __read_mostly = { |
105 | .name = "netbios-ns", | |
106 | .tuple.src.l3num = AF_INET, | |
107 | .tuple.src.u.udp.port = __constant_htons(NMBD_PORT), | |
108 | .tuple.dst.protonum = IPPROTO_UDP, | |
92703eee PM |
109 | .me = THIS_MODULE, |
110 | .help = help, | |
6002f266 | 111 | .expect_policy = &exp_policy, |
92703eee PM |
112 | }; |
113 | ||
114 | static int __init nf_conntrack_netbios_ns_init(void) | |
115 | { | |
6002f266 | 116 | exp_policy.timeout = timeout; |
92703eee PM |
117 | return nf_conntrack_helper_register(&helper); |
118 | } | |
119 | ||
120 | static void __exit nf_conntrack_netbios_ns_fini(void) | |
121 | { | |
122 | nf_conntrack_helper_unregister(&helper); | |
123 | } | |
124 | ||
125 | module_init(nf_conntrack_netbios_ns_init); | |
126 | module_exit(nf_conntrack_netbios_ns_fini); |